1. Field of the Invention
The present invention relates to the structure of a plasma display panel (referred to as a PDP hereinafter), and particularly to the structure of an AC surface discharge type PDP and a plasma display device using the PDP.
2. Description of the Background Art
FIG. 20 is a perspective view schematically showing the structure of a conventional PDP 300. For convenience of explanation, FIG. 20 shows the front substrate 12 and the back substrate 1 separated from each other, but in practice the front substrate 12 is placed so that the edges of the barrier ribs 2 abut on a protective film 14 described later. Also in FIG. 20, a dielectric film 13, described later, and the protective film 14 formed on the dielectric film 13 are shown with broken lines, so that the configuration of transparent electrodes 6 etc. can be seen. FIG. 21 is a plan view schematically showing the structure of the PDP 300; for convenience of explanation, FIG. 21 does not show the front substrate 12, dielectric film 13, protective film 14, phosphors 3 and address electrodes 7. FIG. 22 is a sectional view schematically showing the structure of the PDP 300 taken along the line Hxe2x80x94H in FIG. 21; FIG. 22 shows the front substrate 12, dielectric film 13, protective film 14 and phosphors 3 which are not shown in FIG. 21. FIG. 22 does not show the address electrodes 7.
The front substrate 12 and the back substrate 1 are disposed in parallel to face each other at a given distance. The space between the front substrate 12 and the back substrate 1 is partitioned into a plurality of independent cell spaces 8 by the grid-like barrier ribs (also referred to as ribs) 2 formed on the back substrate 1. Such structure of the barrier ribs 2 is called a waffle rib structure.
The front substrate 12 forms the display surface; on the front substrate 12, bus electrodes 4X and 5Y, transparent electrodes 6 and black stripes 16 are formed on the side facing the back substrate 1. The dielectric film 13 is formed to cover the bus electrodes 4X and 5Y, the transparent electrodes 6 and the black stripes 16, and the protective film 14 is formed thereon. The bus electrodes 4X and 5Y are formed of a double-layered structure of black silver and white silver, the transparent electrodes 6 are formed of an ITO film (an alloy oxide film of indium and tin), the protective film 14 is formed of an MgO (magnesium oxide) film, and the black stripes 16 are formed of a black insulating material. The bus electrodes 4X and 5Y and the black stripes 16 are disposed so that, when the front substrate 12 and the back substrate 1 are bonded together, they overlap the barrier ribs 2, seen from the display surface. The black stripes 16, disposed between the bus electrodes 4X and 5Y, are formed after formation of the bus electrodes 4X and 5Y. Each transparent electrode 6 is T-shaped, with its one end connected to the bus electrode 4X or 5Y. The transparent electrodes 6 protrude over the cell spaces 8 from the connections with the bus electrodes 4X and 5Y. The T-shaped electrodes contribute to appropriate control of the discharge spreading to enhance the luminous efficiency. In the PDP 300, the transparent electrodes 6 extending from the bus electrodes 4X and the transparent electrodes 6 extending from the bus electrodes 5Y form pairs to produce given discharges.
The back substrate 1 has address electrodes 7 which three-dimensionally intersect with the bus electrodes 4X and 5Y; the address electrodes 7 are disposed approximately in the middle of the cell spaces 8. A dielectric layer 15 is formed on the back substrate 1 to cover the address electrodes 7 and the grid-like barrier ribs 2 are formed thereon.
A phosphor 3R for red (R) emission, a phosphor 3G for green (G) emission, or a phosphor 3B for blue (B) emission (referred to also as xe2x80x9cphosphors 3xe2x80x9d together) is applied in the cell spaces 8 which are formed by the back substrate 1, the barrier ribs 2 and the front substrate 12; all cell spaces 8 thus form discharge cells. More specifically, the phosphors 3 are applied on the back substrate 1 and the side surfaces of the barrier ribs 2 forming the cell spaces 8. When the direction in which the bus electrodes 4X and 5Y extend is taken as a row direction and the direction in which the address electrodes 7 extend is taken as a column direction, the phosphors 3R, 3G and 3B are applied in the cell spaces 8 according to a given order among columns.
In the PDP 300, in order to secure an exhaust path for vacuum evacuation, the dielectric film 13 and the protective film 14 are raised on the bus electrodes 4X and 5Y above the remaining area. That is to say, the barrier ribs 2 extending in the row direction abut on the protective film 14 but the barrier ribs 2 extending in the column direction do not abut on the protective film 14. As a result, the cell spaces 8 are not perfectly closed and an exhaust path is thus ensured. The gap between the barrier ribs 2 and the protective film 14 shown in FIG. 22 illustrates this exhaust path.
A PDP having the structure shown in FIG. 20 is described in Video Information Media Society Journal Vol. 54, No.8, pp.1180 to 1184, for example.
In this conventional PDP 300 where all cell spaces 8 form discharge cells which adjoin each other, a discharge in a cell space 8 may induce other cell spaces 8 to cause erroneous discharges. For example, when there is a gap from the first between the edge of a barrier rib 2 and part of the front substrate 12 facing the barrier rib 2, or when a barrier rib 2 is cut or broken to form a gap during the manufacturing process of the PDP, charged particles under discharge may diffuse through the gap into adjacent cell spaces 8, possibly causing erroneous discharge over the barrier ribs 2.
Also, as shown in FIG. 22, the light produced in the cell space 8 includes light 21 which travels directly to the display surface and light 22 which penetrates into the barrier ribs 2 toward adjacent cell spaces 8. While the phosphors 3 have high reflectance and reflects light without loss, the barrier ribs 2 involve large loss of light. Accordingly the light 22 traveling toward adjacent cell spaces 8 is repeatedly reflected in the barrier ribs 2 and attenuated when taken out to the display surface. This causes the problem that, in the light produced in the cell space 8, the light traveling toward the adjacent cell spaces 8 cannot be effectively taken out onto the display surface.
A first aspect of the present invention is directed to a plasma display panel comprising: a first substrate forming a display surface; a second substrate placed to face the first substrate at a given distance; and barrier ribs sectioning a space between the first substrate and the second substrate into a plurality of independent cell spaces; wherein the plurality of cell spaces comprise a plurality of discharge cells and a plurality of non-discharge cells, and the plurality of discharge cells and the plurality of non-discharge cells are arranged so that each the discharge cell adjoins at least one the non-discharge cell.
Preferably, according to a second aspect of the present invention, in the plasma display panel of the first aspect, a phosphor is applied in the discharge cells and no phosphor is applied in the non-discharge cells.
Preferably, according to a third aspect of the present invention, the plasma display panel of the first aspect further comprises black insulating films provided on the second substrate in regions corresponding to the non-discharge cells.
Preferably, according to a fourth aspect of the present invention, the plasma display panel of the first aspect further comprises first reflection films provided on sides of the barrier ribs in regions corresponding to the non-discharge cells, and black insulating patterns provided on the first substrate in the regions corresponding to the non-discharge cells.
Preferably, according to a fifth aspect of the present invention, in the plasma display panel of the fourth aspect, the first reflection films are provided also on the second substrate in the regions corresponding to the non-discharge cells.
Preferably, according to a sixth aspect of the present invention, in the plasma display panel of the fourth or fifth aspect, the black insulating patterns on the first substrate are partially provided also in regions facing the barrier ribs.
Preferably, according to a seventh aspect of the present invention, in the plasma display panel of any of the fourth through sixth aspects, the first reflection films are formed of a phosphor.
Preferably, according to an eighth aspect of the present invention, the plasma display panel of any of the fourth through seventh aspects further comprises second reflection films provided on the black insulating patterns.
Preferably, according to a ninth aspect of the present invention, in the plasma display panel of the eighth aspect, the second reflection films are formed of a phosphor.
Preferably, according to a tenth aspect of the present invention, the plasma display panel of the first aspect further comprises: reflection films provided on sides of the barrier ribs in regions corresponding to the non-discharge cells; and black insulating films provided on the reflection films and on the second substrate in the regions corresponding to the non-discharge cells.
Preferably, according to an eleventh aspect of the present invention, the plasma display panel of the first aspect further comprises reflection films provided on sides of the barrier ribs in regions corresponding to the non-discharge cells and on the second substrate in the regions corresponding to the non-discharge cells, and black insulating films provided on the reflection films.
Preferably, according to a twelfth aspect of the present invention, in the plasma display panel of the tenth or eleventh aspect, the second reflection films are formed of a phosphor.
Preferably, according to a thirteenth aspect of the present invention, the plasma display panel of the first aspect further comprises sustain electrodes comprising first electrodes and second electrodes provided on the first substrate, wherein the first electrodes on the first substrate are arranged over the barrier ribs along a plurality of the discharge cells, and the second electrodes on the first substrate are arranged to protrude from the first electrodes only over the discharge cells.
Preferably, according to a fourteenth aspect of the present invention, in the plasma display panel of the thirteenth aspect, the first electrodes are arranged over the barrier ribs while being shifted toward the non-discharge cells.
Preferably, according to a fifteenth aspect of the present invention, in the plasma display panel of the first aspect, the barrier ribs comprise cuts formed in parts which face the first substrate, the cuts connecting adjacent the cell spaces.
Preferably, according to a sixteenth aspect of the present invention, in the plasma display panel of the first aspect, the first substrate comprises indentations formed in regions facing the barrier ribs, the indentations connecting adjacent the cell spaces.
Preferably, according to a seventeenth aspect of the present invention, in the plasma display panel of any of the first through sixteenth aspects, the discharge cells and the non-discharge cells are arranged in a matrix, and the discharge cells and the non-discharge cells are alternated horizontally and vertically.
Preferably, according to an eighteenth aspect of the present invention, in the plasma display panel of any of the first through seventeenth aspects, the discharge cells occupy a larger area in the display surface than the non-discharge cells.
A nineteenth aspect of the present invention is directed to a plasma display device comprising the plasma display panel of any of the first through eighteenth aspects.
According to the first aspect of the invention, the discharge cells do not adjoin each other, which suppresses and prevents erroneous discharge in discharge cells induced by discharge in other discharge cells.
According to the second aspect, since no phosphor is applied in the non-discharge cells, light traveling toward the non-discharge cells do not repeat reflection within the barrier ribs. Accordingly the light can be taken out to the display surface with smaller loss caused in the barrier ribs, thus providing improved luminous efficiency.
According to the third aspect, black insulating films are provided on the second substrate in regions corresponding to the non-discharge cells, which absorb external light such as room light coming from the display surface into the non-discharge cells. The external light reflected at the second substrate and taken out onto the display surface is thus attenuated, which enhances the bright room contrast.
According to the fourth aspect, reflection films are provided on the sides of the barrier ribs in regions corresponding to the non-discharge cells, so that light traveling toward the non-discharge cells travels in the barrier ribs and is taken out onto the display surface. The light thus do not spread and sharper image can be obtained.
Furthermore, black insulating patterns are provided on the first substrate in the regions corresponding to the non-discharge cells, which absorb external light such as room light coming from the display surface toward the non-discharge cells. The external light reflected at the second substrate and taken out onto the display surface is thus attenuated, which further improves the bright room contrast.
According to the fifth aspect, the reflection films are provided not only on the sides of the barrier ribs but also on the second substrate in the regions corresponding to the non-discharge cells, and the reflection films can be formed in a single process. This offers enhanced manufacturing efficiency.
According to the sixth aspect, the black insulating patterns are provided not only on the first substrate in the regions corresponding to the non-discharge cells but also partially on the first substrate in regions facing the barrier ribs. Therefore the black parts occupy a larger area seen from the display surface. A larger amount of external light can thus be absorbed to further enhance the bright room contrast.
According to the seventh aspect, since the first reflection films are formed of a phosphor, for example if the phosphor applied in the discharge cells and the phosphor of the first reflection films are made of the same material, the material cost can be reduced.
According to the eighth aspect, reflection films are provided on the black insulating patterns, so that light entering the non-discharge cells can be taken out onto the display surface without being absorbed by the black insulating patterns. This further enhances the luminous efficiency.
According to the ninth aspect, since the second reflection films are formed of a phosphor, for example if the phosphor applied in the discharge cells and the phosphor of the first and second reflection films are made of the same material, the material cost can be reduced.
According to the tenth aspect, reflection films are provided on the sides of the barrier ribs in the regions corresponding to the non-discharge cells and black insulating films are provided on the reflection films and on the second substrate in the regions corresponding to the non-discharge cells. Sharper image can be obtained and the bright room contrast can be further enhanced with a structure different from that of the fourth aspect.
According to the eleventh aspect, the reflection films are provided not only on the sides of the barrier ribs but also on the second substrate in the regions corresponding to the non-discharge cells, and the reflection films can be formed in a single process. This further enhances the manufacturing efficiency.
According to the twelfth aspect, since the reflection films are formed of a phosphor, for example if the phosphor applied in the discharge cells and the phosphor of the reflection films are made of the same material, the material cost can be reduced.
According to the thirteenth aspect, the first electrodes are arranged on the first substrate over the barrier ribs along a plurality of discharge cells, so that the light produced from the phosphor can be taken out onto the display surface without being blocked by the first electrodes. This enhances the luminous efficiency.
According to the fourteenth aspect, the first electrodes arranged over the barrier ribs are shifted toward the non-discharge cells. Accordingly, even if a slight positional error occurs in bonding the first substrate and the second substrate together, the first electrodes will not extend over the discharge cell regions. This allows the precision in relatively positioning the first substrate and the second substrate to be relaxed, further effectively preventing reduction in emission luminance.
According to the fifteenth aspect, the barrier ribs have cuts formed in parts which face the first substrate to connect adjacent cell spaces, so that the gap area between the barrier ribs and the protective film can be smaller. It is then possible to prevent charged particles produced by discharge in the discharge cells from spreading into adjacent cell spaces, so as to suppress and prevent erroneous discharge in other discharge cells.
According to the sixteenth aspect, the first substrate has indentations formed in parts which face the barrier ribs to connect adjacent cell spaces. An exhaust path for vacuum evacuation can thus be ensured with a structure different from that of the fifteenth aspect.
According to the seventeenth aspect, the discharge cells and the non-discharge cells are arranged in a matrix and the discharge cells and the non-discharge cells are alternately arranged in length and width directions. Accordingly a larger number of non-discharge cells adjoin the discharge cells. It is thus possible to take out a larger amount of light onto the display surface with smaller loss caused in the barrier ribs, which further enhances the luminous efficiency.
According to the eighteenth aspect, the discharge cells occupy a larger area in the display surface than the non-discharge cells. A larger area can thus contribute to image display and the display area can be used more efficiently.
According to the nineteenth aspect, a plasma display device has the plasma display panel of any one of the first to eighteenth aspects. A plasma display device having any one of the effects of the first to eighteenth aspects can thus be obtained.
The present invention has been made to solve the problems mentioned earlier, and an object of the present invention is to provide a PDP with improved luminous efficiency which can prevent erroneous discharge in adjacent cell spaces 8 and which can effectively take out light produced in the cell spaces 8, and a plasma display device having that PDP.
These and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.